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United States Patent | 5,155,454 |
Amoroso | October 13, 1992 |
A Minimum-Shift Keying (MSK) modulator is described, wherein a feedback scheme is used in combination with a precise frequency reference to enable the production of MSK modulation at the output of an off-the-shelf voltage controlled oscillator (VCO). The upper and lower drive voltages for the VCO, corresponding to the upper and lower frequencies characteristic of MSK, are individually and independently corrected to compensate for imprecisions or fluctuations in the VCO characteristics. The correction increments are derived from phase excursion measurements over individual keying intervals.
Inventors: | Amoroso; Frank (Santa Ana, CA) |
Assignee: | Hughes Aircraft Company (Los Angeles, CA) |
Appl. No.: | 659591 |
Filed: | February 20, 1991 |
Current U.S. Class: | 332/100; 375/305; 375/306 |
Intern'l Class: | H04L 027/12 |
Field of Search: | 332/100,101,102 375/47,64,65, |
3731233 | May., 1973 | Hutchinson | 332/101. |
F. Amoroso and J. A. Kivett, "Simplified MSK signalling technique," IEEE Transactions on Communications, vol. COM-25, No. 4, pp. 433-441, Apr. 1977. F. Amoroso, "Loss of SNR in low pass filtered FM/MSK," IEEE MILCOM '86, paper 40.2, Monterey, CA, Oct. 5-9, 1986. |